3D X-ray Inspection for Semiconductor Vertical Profiles
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Solution Overview
Problem
Current methods for forming three-dimensional images of patterns in semiconductor devices, such as V-SEM and TEM, require destructive analysis and are time-consuming, making them inadequate for inspecting fine patterns and contact holes below 100 nanometers without fracturing the sample.
Innovation Solution
A method and apparatus that use X-rays to form three-dimensional images by measuring electromagnetic wave intensities from both the inspection pattern and a reference pattern with similar surface shape and material properties, decomposing the intensity function into start and characteristic functions, and iteratively integrating to determine an optimal vertical profile function without fracturing the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If V-SEM or TEM is used to analyze the vertical profile of the pattern, then measurement precision is improved, but the sample pattern must be fractured and destroyed
Solution Approach 1:
The patent replaces the mechanical fracturing process required by V-SEM and TEM with a non-contact X-ray measurement system. The X-ray source and detector measure electromagnetic wave intensities through the substrate without physical contact, eliminating the need to break the sample while obtaining vertical profile information.
Solution Approach 2:
The patent introduces X-rays as an intermediary medium to obtain information about the vertical profile. The X-rays pass through the substrate and interact with the pattern structures, carrying information about the vertical profile to the detector without requiring direct mechanical access to the cross-section.
2Measurement precision
If V-SEM or TEM is used to form three-dimensional images, then analysis performance is improved, but time consumption increases due to destructive preparation
Solution Approach 1:
The patent performs preliminary non-destructive measurements using X-rays to obtain vertical profile information directly from the intact sample. This eliminates the time-consuming sample preparation steps (fracturing, mounting, coating) required by conventional methods, allowing direct measurement and faster analysis.
3Reliability
If optical methods are used for vertical profile analysis, then non-destructive measurement is achieved, but process complexity increases
Solution Approach 1:
The patent changes the physical parameter used for measurement from visible light (optical methods) to X-rays. This parameter change allows penetration through the substrate and direct interaction with the pattern structures, simplifying the measurement process while maintaining non-destructive characteristics and reducing data processing complexity through the iterative decomposition method.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the formation of three-dimensional images without damaging the substrate, allowing for efficient detection of defects in inspection patterns, thereby improving inspection efficiency and reliability for semiconductor devices.
Implementation Method 1
various research has been conducted for analyzing a structure of a vertical profile of the pattern. A vertical scanning electron microscope (V-SEM) and a transmission electron microscope (TEM) have been used for analyzing the vertical profile of the pattern
Implementation Method 2
An intensity of an inspection electromagnetic wave is measured from the inspection pattern on a substrate, and an intensity of a reference electromagnetic wave is also measured from a reference pattern on a reference specimen
Data Source
AI summary
In a method and apparatus for forming a three-dimensional image for an inspection pattern, a reference intensity function of an inspection X-ray is formed in accordance with a continuous scanning depth, and is differentiated with respect to the scanning depth. The differential reference intensity function is decomposed into a start function and a characteristic function. The differential reference intensity function is then repeatedly integrated while a temporary vertical profile function is substituted for the start function until the temporary intensity of a reference X-ray is within an allowable error range. The temporary vertical profile function satisfying the error range is selected as an optimal vertical profile function. A surface shape is combined to the optimal vertical profile function along a depth of the inspection pattern to thereby form the three-dimensional image for the inspection pattern.